Cyclooctene

COE

• 931-88-4 (mixture of isomers )
• 931-87-3 [( Z)- cyclooctene ]

Inflammatory, pale brown, odorless liquid

Liquid

0.85 g · cm -3

-16 ° C.

148 ° C.

8 hPa ( 20 ° C)

1.469 at 20 ° C.

Risk

Template: Infobox chemical / molecular formula search available

Cyclooctene is a chemical compound selected from the group of unsaturated cyclic hydrocarbons ( cycloalkenes of precisely ).

Production and representation

(Z)- cyclooctene is obtained in good yield by hydrogenation of cyclooctatetraene or by Cope elimination of the N, N- Dimethylcyclooctylaminoxid. The racemic mixture of ( E) - ( )- cyclooctene and (S) - (-) -cyclooctene arises ( in addition to ( Z)- cyclooctene ) by pyrolysis of N, N, N- Trimethylcyclooctylammoniumhydroxid.

A very elegant way for the synthesis of (E)- cyclooctene is a Corey - Winter elimination starting from ( E) -1,2- cyclooctanediol:

(E)- cyclooctene can also be obtained by photochemical isomerization of (Z ) -cyclooctene. Although the balance is located here at the side of the (Z)- cyclooctene, the reaction by removal of the (E ) isomer by complexing with silver can be driven to completion.

Technically, it is prepared by the selective hydrogenation of 1,5- cyclooctadiene, which is accessible by a method of Wilke by dimerization of 1,3-butadiene.

Properties

Cyclooctene, there are three isomers: (Z)- cyclooctene, (Pr ) - ( E)- cyclooctene (PS) - (E)- cyclooctene. The ring size in cyclooctene allows just that the double bond of both (E) - and ( Z) - may be configured. (E)- cyclooctene is due to the lack of rotating mirror axis optically active, therefore chiral. P from the R / S- descriptors indicates this is that it is a planar chirality.

Use

By ring-opening polymerization of ( Z)- cyclooctene polyoctenamer is obtained which is used as a component in elastomers. Ozonolysis of the alkene gives octanedioic acid ( suberic acid, suberic acid ), which serves for the production of plasticizers or polyamides. Thermolysis of (Z)- cyclooctene provides octa- 1 ,7-diene, which is used as a monomer in the rubber and plastics industry. Via several intermediate steps, there is also the production of various perfumes.

(Z)- cyclooctene is a popular substrate for epoxidation. These usually run from very selective because the lowest energy conformation of (Z) -cyclooctene significantly complicates the formation of allylic byproducts.

Safety

The vapors of cyclooctene can combine with air when heated above its flash point (24 ° C) to form an explosive mixture. This is possible even at elevated ambient temperature.